What is broken in my charging system?

[RBoss]

Hi all,

I'm posting this thread as I can't figure out what is broken in my charging system. I have read multiple existing threads on how to diagnose which part in my charging system is broken but I am not able to figure it out (yet). I'll start with the storyline.

1. Rebuilt my bike (frame, engine, etc.), worked well and had a few first test rides. After the first 150km I ran out of fuel (didn't know) and was not able to turn the starter motor (so I thought about, and posted about a seized engine). After transporting the bike with a trailer and starting to take the bike apart I figured out it was a combination of no gas and a dead battery.

2. The gas problem was solved, but the battery not yet. I replaced the wiring harness (not the sub harness at the electronics side) as it was in bad shape. I also replaced the rectifier and regulator for a combination module. I hoped after that it was solved but unfortunately not.
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3. As I couldnt see any issues on the stator or broken wires anywhere I tested with another new regulator/rectifier from the supplier. Same issue, but I ruled out a faulty regulator/rectifier

4. I tested the stator by seeing if the yellow wires have continuity to the frame (they don't)

5. I tested the stator green and white wires to the battery poles directly (I attached a video of this). This is where I am unable to get a the values provided by the book. (attached a picture). I do however get 13.7 ish volts at 3000-4000 rpm.
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link to my test video: https://youtube.com/shorts/LlkHQZoDTlc

My question: would you say the stator is OK? And what would you look for next?

Thanks!
Ruben

[Bryanj]

If you got charge when green and white connected to battery then i dont care what make or how many combined units you have they are either duff or wired wrong and if wired wrong could have been made duff by that

[RBoss]

If you got charge when green and white connected to battery then i dont care what make or how many combined units you have they are either duff or wired wrong and if wired wrong could have been made duff by that

So the video shows the stator is OK?

[Bryanj]

Cant watch videos on my dumfone and laptop died.
If you get ac voltage at all 3 pairs of yellow leads on stator (50-70v ac) when disconnected but field(green and white) powered both stator and field are ok.
You said 13.7 v dc when field powered which equates to approx same so yes your coils are ok, this is distance diagnosis from your readings so not guaranteed

[deltarider]

Bryan is right. You could do another measurement with AC selected, but I'm confident there will be nothing wrong with the alternator. I haven't heard of one case yet. Rectifiers also rarely become damaged. When polarity is not observed, it can happen within a second however. Some modern batteries have terminals that may lead to confusion! The OEM Toshiba regulator has a very good reputation. Not that long ago a German engineer in the German forum argued convincingly, it does an even better job than aftermarket products as the oldstyle resistor more or less senses the ambient temperature and so 'adjusts' the voltage. When he did the research, his Toshiba had travelled near 200.000 km. Also my OEM components are still alive and perform as they should.
When you do the measurement as Honda prescribes in p.94 of the Shop Manual Honda CB500-550, be aware that the scheme at the bottom is quite theoretical. What I mean is, that the condition of the battery plays a role, so you might not see those wonderful voltages immediately. A better test is to go for a ride, find a stretch where you can maintain a cruising speed having an RPM of say at least 4500. Then monitor DC voltages presented on your DMM (in your tankbag?). After some time, you should witness the voltages that are in the scheme of p.94. I'd abstain from measuring the current (A). With the ammeter connected as shown in the top of p.94, do not operate the electric starter! A mistake is easily made and your test wires will melt.
BTW, glad you're back and good to learn your engine has survived. 

[Bryanj]

I would add to that that whilst the rectifier MAY survive a short time of reverse polarity the electronic regulator definately wont.
The black wire at the regulator should be at the same positive volts as the positive of the battery, any less will give wrong charging

[RBoss]

@Delta, thanks for your thoughts! I'm indeed very happy it was not a seized engine after all... I had to process the mistake of thinking it being a seized engine a bit though. Although the combination of no gas and a dead battery was quite a coincidence.  Anyway it (almost) works again!

Happy to read that the alternator is probably in good shape. I think I might perform the driving test you describe. Also I am thinking of replacing the sub-wiring harness and the starter solenoid as they do have some corroded contacts. My OEM rectifier unfortunately lost a contact due to corrosion so that one had to go, and the replacement unit is a combination so I thought I might as well replace the regulator.

Next step I think is to replace some wiring and the starter solenoid to rule out more bad wiring and contacts...

Thanks!